The prior art is replete with a wide variety of approaches to monitoring and signaling vehicle tire pressure. The enclosed Information Disclosure Statement describes a large number of patents in this area ranging from the old Pat. No. 2,948,256 to Tapp through 4,510,484 to Snider. Several of these prior patents show a tire pressure indicator that is emplaced on the valve stem location. This is disadvantageous in that it tends to unbalance the tire and produce a signal that is subject to false alarms introduced by bounce or centrifugal force.
In others, tire pressure monitors are incorporated in vehicles having pneumatic tires to continuously or periodically measure air pressure within the tires and to alert the driver, or operator, should the pressure in one of the tires fall below a predetermined value and these have included units having self-contained batteries, transmitters affixed near the center of the wheel so as to minimize the unbalance introduced, periodic emission of pulses by the transmitter proportional to tire pressure such that these can be monitored and the like.
Consideration of the prior art shows the prior art has failed to produce the following features considered desirable and not heretofore made available.
(1) The tire pressure monitoring system should have a means for rejecting false alarms caused by bounce or centrifugal force;
(2) The tire pressure monitoring system should have a sensor remote from the tire itself not interiorly thereof;
(3) The tire pressure monitoring system should have a plurality of transmitters and receivers where each transmitter and receiver has its own battery. It is acceptable to operate the warning system off the truck electrical system, since the only time the operator would be monitoring the warning system would be when the truck was in operation. It is desirable that each transmitter and receiver have a means for testing the battery and conserve the battery as much as possible so that it operates only under a low tire pressure condition;
(4) There should be a connector and compatibility of components which allow changing between towing and towed vehicle components of the multi-wheel truck or the like;
(5) There should be a delay between sensing the low pressure and sounding the alarm in the cab in order that there be a safeguard against false alarms, whether from bounce, centrifugal force or passing another compatible vehicle; and finally,
(6) There should be an indicator on the hub where the low tire pressure is sensed to facilitate locating the low tire by the operator of the vehicle once the operator has been given a warning.